(a) Field of the Invention
The invention relates to a method for correcting a defect pixel.
(b) Description of the Related Art
An image signal passing through an image sensor which converts an external image into an electric signal, is converted into a digital image signal through sampling and quantizing processes. The image sensor for acquiring the image has a plurality of pixels.
In the case of a digital image input device such as a digital camera, a mobile phone with a camera, and the like, arrangement of a color filter such as a Bayer filter which extracts only a single color in one pixel position in order to reduce the number of color samples is used and a red, green and blue (“RGB”) full-color image is created by processing a sensor Bayer pattern outputted by the image sensor through an image signal process (“ISP”).
In the case of the Bayer sensor, defect pixels are generated due to a processing problem or various environmental factors in a pick-up process.
The defect pixels are largely divided into dead pixels and hot pixels. The dead pixel is a phenomenon in which a fixed value of black or white is shown because the pixel itself does not represent the color by a sensor processing problem in general. On the other hand, the hot pixel as a noise of the pixel is generated in the case where the temperature of the sensor is increased due to the use of the camera for a long time, where sensitivity of the sensor is increased by increasing International Standarization Organization (“ISO”) speed, or where an exposure time of light is increased by lengthening a shutter speed.
In photographing, the defect pixels as described above have a serious effect on image quality. As a technique for removing the dead pixel as one of the defect pixels, a method of replacing a current input pixel with a neighboring pixel value or an average value has been used when the current input pixel coincides with stored position information, by separately allocating a memory or register capable of designating a position of the dead pixel. In addition, by comparing a level difference value between the current input pixel and the neighboring pixels with a reference value, when the difference is large, a method of determining the current input pixel as the hot pixel and processing it as the average value has been used.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.